Classical Cepheids and the spiral structure of the milky way

Дамбис, А. К.; Бердников, Л. Н.; Efremov, Yu. N.; Kniazev, A. Y.; Rastorguev, A. S.; Glushkova, E. V.; Kravtsov, V. V.; Turner, D. G.; Majaess, D.; Sefako, Ramotholo

doi:10.1134/s1063773715090017

Cited by 50 publications

(52 citation statements)

References 26 publications

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“…Sample 2 gives 50 equations for Vr and 32 equations for µ l . We solve the equations for the line-of-sight velocities and proper motions jointly and use weight factors to allow for observational errors and "cosmic" velocity dispersion (see also Dambis, Mel'nik & Rastorguev 1995;Mel'nik, Dambis & Rastorguev 1999. We use standard least square method (Press at al.…”

Section: Galactic Rotation Curvementioning

confidence: 99%

“…1987) to solve the systems of 126 (sample 1) and 82 (sample 2) equations, which are linear in the parameters Ω0, Ω ′ 0 , Ω ′′ 0 , u0, and v0. We adopt a solar Galactocentric distance of R0 = 7.5 kpc (Rastorguev et al 1994;Dambis, Mel'nik & Rastorguev 1995;Glushkova et al 1998;Nikiforov 2004;Feast et al 2008;Groenewegen, Udalski & Bono 2008;Reid at al. 2009b;Dambis et al 2013;Francis & Anderson 2014;Boehle et al 2016;Branham 2017).…”

Section: Galactic Rotation Curvementioning

confidence: 99%

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Kinematics of OB-associations in Gaia epoch

Melnik

Дамбис

2017

Monthly Notices of the Royal Astronomical Society

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We use stellar proper motions from the TGAS catalog to study the kinematics of OBassociations. The TGAS proper motions of OB-associations generally agree well with the Hipparcos proper motions. The parameters of the Galactic rotation curve obtained with TGAS and Hipparcos proper motions agree within the errors. The average onedimensional velocity dispersion inside 18 OB-associations with more than 10 TGAS stars is σ v = 3.9 km s −1 , which is considerably smaller, by a factor of 0.4, than the velocity dispersions derived from Hipparcos data. The effective contribution from orbital motions of binary OB-stars into the velocity dispersion σ v inside OB-associations is σ b = 1.2 km s −1 . The median virial and stellar masses of OB-associations are equal to 7.1 10 5 and 9.0 10 3 M ⊙ , respectively. Thus OB-associations must be unbound objects provided they do not include a lot of dense gas. The median star-formation efficiency is ǫ = 2.1 percent. Nearly one third of stars of OB-associations must lie outside their tidal radius. We found that the Per OB1 and Car OB1 associations are expanding with the expansion started in a small region of 11-27 pc 7-10 Myr ago. The average expansion velocity is 6.3 km s −1 .

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Section: Galactic Rotation Curvementioning

confidence: 99%

Section: Galactic Rotation Curvementioning

confidence: 99%

Kinematics of OB-associations in Gaia epoch

Melnik

Дамбис

2017

Monthly Notices of the Royal Astronomical Society

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“…Calzetti et al 2005;Grosbøl & Dottori 2012, and references therein) which are embedded into a smooth stellar disc. There are different tracers of spiral structure in galaxies (including our own Milky Way), such as Hii regions (Georgelin & Georgelin 1976;Hou et al 2009;Honig & Reid 2015), OB associations (Regan & Wilson 1993), population I Cepheids (Dambis et al 2015;Skowron et al 2019), giant molecular clouds (Cohen et al 1986;Vogel et al 1988;Wiklind et al 1990), enhanced gas density (Grabelsky et al 1987; ⋆ E-mail: s.s.savchenko@spbu.ru Engargiola et al 2003;Sánchez-Menguiano et al 2017), and dust clouds (Holwerda et al 2005).…”

Section: Introductionmentioning

confidence: 99%

A multiwavelength study of spiral structure in galaxies. I. General characteristics in the optical

Савченко

Marchuk

Mosenkov

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Different spiral generation mechanisms are expected to produce different morphological and kinematic features. In this first paper in a series we carefully study the parameters of spiral structure in 155 face-on spiral galaxies, selected from the Sloan Digital Sky Survey, in the three gri bands. We use a method for deriving a set of parameters of spiral structure, such as the width of the spiral arms, their fraction to the total galaxy luminosity and their colour, which have not been properly studied before. Our method is based on an analysis of a set of photometric cuts perpendicular to the direction of a spiral arm. Based on the results of our study, we compare the main three classes of spirals: grand design, multi-armed and flocculent. We conclude that: i) for the vast majority of galaxies (86%) we observe an increase of their arm width with galactocentric distance; ii) more luminous spirals in grand design galaxies exhibit smaller variations of the pitch angle with radius than less luminous grand design spirals; iii) grand design galaxies show less difference between the pitch angles of individual arms than multi-armed galaxies. Apart from these distinctive features, all three spiral classes do not differ significantly by their pitch angle, arm width, width asymmetry, and environment. Wavelength dependence is found only for the arm fraction. Therefore, observationally we find no strong difference (except for the view and number of arms) between grand design, multi-armed and flocculent spirals in the sample galaxies.

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“…The 'spiral pattern' rows refer to the 'pattern speed of the spiral density wave' at the Sun's location (set at 8.0 kpc), while various published models [81][82][83][84][85] found it an angular velocity value (column 4), from which equation 6 here yielded its orbital speed at this radius (velocity in column 6), while equation 7 yielded an orbital period (column 8). The word 'circular' is mathematical, as the model-dependent pattern orbit may not be circular.…”

Section: Angular Rotation and Orbitsmentioning

confidence: 99%

A guided map to the spiral arms in the galactic disk of the Milky Way

Vallée

2017

Astronomical Review

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An up-to-date overview of the recent history is given, aiming is to present a helpful working guide to the literature and at the same time introduce key systems and observational results, starting from the Sun and going toward the Galactic Center and parts of the Zona Galactica Incognita, and beyond. We start by presenting an observational view of the Milky Way's disk plane (cartographic, dynamical, chemical crosscut, magnetic). This included the four long spiral arms in the disk of the Milky Way galaxy, their geometry, components, velocity, their widths and internal layers as well as onion-like ordered offsets, the central galactic bars, arm tangents, arm pitch and arm shape, arm origins near the Galactic Center, and other possible players in the spiral arm, such as the magnetic field and the dark matter content. After, we present a basic analysis of some theoretical predictions from galactic arm formation: numerical simulations or analytical theories, and observations are checked against predictions from various numerical simulations and analytical (theoretical) models.

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Classical Cepheids and the spiral structure of the milky way

Cited by 50 publications

References 26 publications

Kinematics of OB-associations in Gaia epoch

Kinematics of OB-associations in Gaia epoch

A multiwavelength study of spiral structure in galaxies. I. General characteristics in the optical

A guided map to the spiral arms in the galactic disk of the Milky Way

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